docs: def layers(self):
          """gets the service layers"""
          if self._layers is None:
              self.__init()
          lyrs = []
          for lyr in self._layers:
              url = self._url + "/%s" % lyr['id']
              lyr['object'] = MobileServiceLayer(url=url,
                                                 securityHandler=self._securityHandler,
                                                 proxy_url=self._proxy_url,
                                                 proxy_port=self._proxy_port,
                                                 initialize=False)
          return self._layers